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Human Chimera Research's Huge (and Thorny) Potential

IT IS STRIKING just how little we know about human development, especially given we are now decades into the modern era of biology. How is it possible that we understand exquisitely well how worms, fruit flies, and rodents develop, but our own species' development remains a black box?

One big reason is that for a long time, the politics of doing science on human embryos and fetuses have been radioactive. The recent smear campaign against Planned Parenthood’s fetal tissue practices is just the latest example of how these ongoing attacks have had a chilling effect on laws that might advance human developmental biology research. But things are beginning to thaw. On August 4, the National…

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Featured

 Rethinking Humanity: the Chimera Debate

For most of history, part-human part-animal beings have always resided in the realm of fiction and folklore. Recently, however, advances in genetic engineering and microsurgery have brought these creatures into existence. Scientists now have created human-nonhuman chimeras—organisms that have both human cells and animals cells in their bodies. These chimeric animals hold enormous potential for the field of medicine as well as basic research into human physiology. Their utility in science lies in their unique biological integration of both human and animal cells, which can give rise to human tissues and even organs within the body of an animal

 Will Human-Animal Chimeras Cause Moral Confusion? Exploring Public Attitudes

Recent medical research involving human-monkey chimeras, human brain organoids in rats, and the transplantation of a gene-edited pig heart and gene-edited pig kidneys in living human beings have intensified the debate about whether we should create human-animal chimeras for biomedical purposes and, if so, how we should treat them.

Articles of Interest

Chimera research opens new doors to understanding and treating disease

Animals with human cells could provide donor organs or help us understand neuropsychiatric disorders.

Generating Human Organs via Interspecies Chimera Formation: Advances and Barriers

The shortage of human organs for transplantation is a devastating medical problem. One way to expand organ supply is to derive functional organs from patient-specific stem cells. Due to their capacity to grow indefinitely in the laboratory and differentiate into any cell type of the human body, patient-specific pluripotent stem (PS) cells harbor the potential to provide an inexhaustible supply of donor cells for transplantation. However, current efforts to generate functional organs from PS cells have so far been unsuccessful. An alternative and promising strategy is to generate human organs inside large animal species through a technique called interspecies blastocyst complementation.

In the Spotlight: Animal-Human Chimeras

What do we understand by the term chimera? When someone says the word ‘chimera’, the first image that comes to many people’s minds is a fire-breathing female monster with body parts from three different animals (lion, goat and dragon). However, a bit of research about the word ‘chimera’ reveals a less mythical and more scientific definition: an animal containing cells with distinct genotypes – in other words, an animal generated by the combination of cells originally from different embryos.

Natural human chimeras: A review

Human chimeras have been described for nearly 70 years by clinicians, serologists and cytogeneticists. However, it is in the last two decades that chimeras have caught the public attention because of three high profile media reports of a chance finding during parentage testing: The first was a case of a woman, Karen, who was told, following DNA tests of family members for a kidney donor, that two of her three sons could not be hers

Should Human Stem Cells Be Used To Make Partly Human Chimeras?

"The shadow of negativity cast around this research is going to have a major negative impact on any progress going forward," says Sean Wu, a cardiologist and assistant professor of medicine at Stanford University, who helped write the article.

The Case of Lydia Fairchild and Her Chimerism (2002)

In 2002, after applying for government assistance in the state of Washington, Lydia Fairchild was told that her two children were not a genetic match with her and that therefore, biologically, she could not be their mother. Researchers later determined that the genetic mismatch was due to chimerism, a condition in which two genetically distinct cell lines are present in one body. The state accused Fairchild of fraud and filed a lawsuit against her. Following evidence from another case of chimerism documented in The New England Journal of Medicine in a woman named Karen Keegan, Fairchild was able to secure legal counsel and establish evidence of her biological maternity.

The five: chimeras created by science

A chimera is an organism with genetic material from two or more sources. Experiments in the field may save lives but are ethically controversial

Time to rethink the law on part-human chimeras

It may soon be possible to generate human tissues and organs inside of part-human chimeras via a technique known as interspecies blastocyst complementation.

What’s Wrong with Human/Nonhuman Chimera Research?

Stem-cell–based human/nonhuman chimera research involves the transfer of human stem cells into animal hosts at various stages of development. The purpose of this research is to introduce localized human cellular and biological characteristics into laboratory animals to advance stem cell science, developmental biology, and many areas of biomedicine. Human/nonhuman chimera research has existed without much controversy for decades outside of stem cell research, resulting in, for example, mouse models of human cancer and the human immune system.

Resources

3 Human Chimeras That Already Exist

Some people—such as fetuses that absorb a dead twin—have two sets of DNA